Twin lens reflex camera



Jan. 31, 1950 J. H- MCILROY 2,496,059

TWIN LENS REFLEX CAMERA Filed Sept. 7, 1.948 3 Sheets-Sheet 1 IN V EN TOR. JOHN H. MC/L H0) ATTORNEY Jan. 31, 1950 Filed Sept. 7, 1948 J. H. MCILROY 2,496,059

TWIN LENS REFLEX CAMERA 3 Sheets-Sheet 2 3.9 1 53 .440 ,33 1 20 V i 35 I Q 3/ JNVENTOR. 'JOHN H MG/LROY ATTORNEY Patented Jan. 31, 1950 Macvan.;.Manufacturing Compan-y; San Diego,v Calif; a'corporation of California Application- September v'7, 1948; Serial No. 48,001

3 Claims. :(Cl. 95.,.44). 5,

tions;- looking downwardly upon thevsameinrthea. direction of arrows 5,\-5-'as shown-in Fig. .4; Fighfi is anenlarged sectionon line ,6,--6 of-.a1 portions. of Fig.1, looking, inthesdirection ,of the. arrows; andcshowing; in detail, the coordinating mechanism? for actuating-the focusing, controlsw; 1 and; adjusting the viewing screen Fig. is a longitudinalview-cof the main shaft, I and adjacent. connections employed forsactuatingl.

1 By:inventiomrelatesv-to photographic: cameras.,-.- particularly coordinated-twin lens:- reflex, cameras-e having ,cautomaticn means iior the, avoidance of, paraliaxp and objects. aresto provide a. better mechanism r "for operativelys, connecting. the! ad# justmenttof theviewing screenof the finder with the. .means of actuating. the ,f ocusing controls,- ,,so that the same scene is, reproduced simultaneously uponqboth the .areaof theIsaidscreen-andthat of iii.

theysensitizedefilmEur-plate, irrespective. of the disarm the focusing controls; and, tanceaway 'of thersubjectefiomi the camera; to Fig.4; is an enlarged detailedviewof theflcamm bringaboutand maintain a betterioousot theJeX-J. and cam. follower and adjaoentlparts used forge. posurelensso as more vsharply to define. the sub: 1 swinging. the 'mirroruponits pivotalaxis. jectito be photographeda-to .provideracamerarof Referring to the drawing, the camera.,there. this ,characterein which theZL-axes cof bothrthe" shown-comprises the case 8,;finderclens-9, exposure finderivlensrandutheg exposure. lens .whilef'being lens 10, bellows H and 12,. hood=-l3 and plate, focusedaremaintained constantlyin exact paralholder.-|.4. Connecting the. barrels r l5 and .116 or .7 lel relationand inwhich the 'view'ingscreen, is at I the, lenses, 9. and .I0 to ..the front .endsof said .15; thec'same.timesynchronized with saidlenses so as bellows --is thesplate l1, pivotally. securedtop and to displaycpreciselyitheisame image as that re- :bottom by pins l8 and, l9 to lugs 20 and 2.! -to the ceived .uponcthei'surface of thefsensitizedfilmorn rectangular frameM22; the rearmendsjof said' plategto provide a single manually' manipulated bellowsloeing connected: to the @outerT-face vof the means for controlling the" actuating mechanism: adjacent front wall .23,.of theQcasenB. J'Mou'nted for focusing control, together withcoordinating upon an upper corner of theframe 22 and e'x-l mechanism foriadjustingithe 'viewingscreen: t 25 tending routwardlytherefrom.v is the post, 24,?" providela film Lor plateholderwhich maybe set at through which extends laterallyand. in threaded'l. any,v desired angleflwithout;having ,toturnthei engagement therewith thenmicrometer screw 25,:"1 camera from its upright'position, and which when whose. extended end 26 is pivotallyhonnected to so set may be locked in place to renderthe parts the protruding lip Z'I'secured'to the top of plate I! readilyaccessible for inspection',1adjustment, readjacent to thepin I8, andserves to turniona moval, replacementrestoration or repair; and in; vertical axis both of the lenses carried upon said general .to provide an apparatuswhich' is .ecoplateintodesired adjusted angularip'osition. T nomical of construction, efficient inaction and of Extending. through the front wall 23 "of the case prolonged life. and durability." inventioniur- 8, andlregistering with the ,rear ends of *the" ther consists ofother novelfeatures of construe-+ ,bellows ll and I2 are the circularopenings'n and" tion, and combinations andarrangements of parts;- 29,,l'oc'ated one above theother ;.the'* opening -:28 illustrated in ltheldrawing and .more particularly opening'into the hollow of sa'id;case,;and the. open: hereinafter; described .andcclaiine'd. ing 29 registering with the truncated open endi30 Attention is herebyrdirected'to theaccompany= of the' eone 3| aflixed to therinner face of the wall ingqdrawing, illustratinga preferredeiorm of my 4 35 As shown, thecone 3| extends .entirelygacross invention, in which similar numerals of designaa the hollowof the 'caseB from cfrontwalld23 to rear tion refer'to similar'partsithroughoutthe several wall,3.2 thereof; theenlargedflaringropen end"33 views, and in which:- v I I v of said cone registering withtheicircularopening" j Figure 1 is a frontrelevatioii of the camera?" 34 through said wall 32,"and"also'registering'with looking zdirectlyiTintoY'the' "finder";andfldexposurefi theopening 35 in the inner wall of plate holder I 4. lenses thereof; ;and:showin'g"the'viewing hood cat Preferablmfthe ends of thesaid cone are made to het ptm registeriwitnandto .turn'in, rings: 31 aand 3H1,

Fig';2,.is aside elevation of: the'cameraishownin connected to the front. and rear:walls"23 and-"325W Fig'il respectively, of the case 8. f Thewall'of thecone Fig'IBJsarear.elevation of said'camera; 5 3| is of such,material and thickness as to renderf'r' theusame impervious, to the transmission of light" coming from thelinterior of the caseB, whilezper-g "i mittingire'e passageof rays of light coming fromrtv the exposureilens. JD and cast upon the sensitized."v filrnlor plate or theplat'e'holder l4."

is a. view .similarrtoglthatr of F,'ig". 12 but .1 showinghthelcase of thelcamera ,inc.jsec.tion, and; i1 certain partsmbrokenv away I iorzthe." purpose of bettervillustrationaw a Fig." .5 a-aview,.-pf the. iinder-ilens and connece-c Integral with each upright side of the frame 22 are the ears 3! and 38, to which are firmly secured the lens focusing rods 39 and 40, respectively, each mounted to slide forward and back within the passageway 4| of a hollow casting 42, located inside of the case 8, and securely affixed to the front wall 23 thereof, outside of the cone 3!. The top portion of each of said rods is provided with a rack 43 positioned to mesh with a pinion 44a mounted to turn upon a counter shaft 44 journalled in bearings in an upright clevis extension 45 of th casting 42; the said pinion also meshing with the gear 46, out within or mounted upon the shaft 41; which shaft is also journalled in bearings in said extension. Preferably, to prevent either of the racks 43 from being moved outwardly out of engagement with its pinion 44a, I supply the stop pin 43a, the shank of which passes through the inner end of the rack just beyond the last tooth therein and is embedded in the wall of the adjacent focusing rod, and the head of which pin rising above the rack prevents disengagement of said pinion and rack. The said shaft 41, thus engaging with a twin train of gears which serves to activate at the same time the rods 39 and 40, extends across theentire width of the case 8, and is journalled near its ends in bearings in the side walls 48 and 49 of said case; the said ends extending outwardly beyond said sides and having mounted thereon the circumferentially knurled handles 50 and 5|, which handles furnish a convenient means of manually turning the said shaft and focusing the lenses accordingly.

Also secured to one of the countershafts 44 and turning therewith is the cam 441), the periphery of which is shaped and positioned to engage with the heel 52 of the cam follower 53; the upper nd of said follower being mounted upon the protruding end of one of the pair of horizontally disposed trunnions or shafts 55 journalled in the ends of a pair of lugs 51, 51, integral with the sides of the hood l3, and downwardly projecting therefrom.

Extending between said lugs 51, 51, and pivotally mounted upon said trunnions 55, through a pair of trunnion seats 58,58, is the cradle 59; said cradle being in the form of a flat plate with said seats integral therewith and extending upwardly from th sides thereof, and having firmly secured therebetween upon the top of said plate the fiat mirror 50 facing upwardly thereon. Projecting at one side from the front of the lower end of the plate forming the said cradle and inte gral therewith is the arm 6|, the outer end of which is in threaded engagement with the screw 52, the threaded end of which extends downwardly and is positioned to make adjusting contact with the toe 64 of the cam follower 44b. To hold the heel 52 of the cam follower 53 against the cam 44b, I provide the tension spring 440, the ends of which are secured respectively to the top of the cradle 59 and to one of the lugs 51 (see Fig. 4).

Pivotally secured to one side of the upper end of said cradle 59 and to the outer end of the walking beam 66 is the rod 61; the said walking beam being pivotally mounted upon the upper portion of one of the lugs 57, and having its inner end 68 pivotally connected by the rod 69 to a pin secured to an intermediate part of the link 10. Also the outer end of the link 10 is pivotally connected with the central portion or intermediate part of the segmental rest 1|, provided with the arcuate curved top 12, affixed to 4 one side of the hood H. A pair of said rests H are supplied, each secured to an opposite side of the hood and located in exact parallel relation one with the other; the two rests being positioned to permit the frame 73 enclosing the fiat viewing screen 14 to ride arcuately thereon and to be inclined horizontally in respect to said hood. For purposes hereinafter set forth, the said segmental rests H, II, are positioned so that the arcuate curve of their said tops l2, 12, will find its center in the trunnions 55 upon which is pivotally mounted the axis of the cradle 59. As shown, the inner end I5 of the link 10 is secured to the upper edge of the frame 13 by the bolt 15, the threaded shank of which is provided with the compression spring 11, held in place by the nut 19. Also, the outer edge of the frame 13 is connected by the tension spring 18 to a pin or screw 54 secured to the bottom of the lower front side of the hood l3.

In order that all of these moving parts may be in the correct relation and made to act in required coordination, the finder lens 9, when being focused, must be positioned in relation to the mirror 50 so that at any part of the path of said lens the inner extension of the axis of said lens will always pass through th axis of the cradle 59 or the line of the centers of the trunnions 55. Also the relation between the radial or pivotal centers of walking beam 58, cradle 59, curve of segmental rest 1|, link 10 and frame 13 are such that the viewing screen 14 is caused to move two angular degrees for each angular degree moved by the mirror upon the cradle 59; all being within the focusing range of the camera. Th arrange ment of parts being such that the relative movement of the face of the screen in respect to the face of the mirror will be in accordance with the equation z'=F /:n, where z is the distance from the object to be photographed to the first focal point of the lens, and :n' is the lens movement upon being refocussed on an object located at infinity.

Thus, the finder lens is positioned so that the light rays coming from the object to be photographed will be cast upon the surface of the mirror 60, and are reflected therefrom to the viewing screen 14, where said object will be observed by the photographer in its normal upright aspect when looking down through the hood from behind the camera. At the same time the exposure lens I0 is so positioned that the light rays coming from the said object and passing through the hollow of the cone 3| will be cast upon the photographic plate or film carried within the holder [4 at the rear of the camera. Both lenses by reason of their attachment to the plate I! and sequential connections with the frame 22, focusing rods 39 and 40, gear and link train operated by the shaft 41, and handles 50, are equally and simultaneously moved towards or away to or from the object to be photographed.

In order to photograph an object away from the camera, the focusing of the two lenses 9and I 0 requires that they be pulled backwardly by the lens focusing rods 39 and 40 toward the photographic film or plate of the holder H, with the result that the mirror 60 upon its cradle 59 will be caused to swing. to the left, and the reflection of said object cast upon the viewing screen 14 caused to move toward the rear of the camera. On the other hand, to photograph an object close to the camera, the focusing of said lenses requires that they be thrust forward b the said focusing rods away from said photographic plate or film,

with the result that the said mirror will be swung toward the right, and the reflection of said object upon said screen caused to move toward the front of the camera. Thus the changing in position of the reflected object cast upon the viewing screen effected by the foregoing means will compensate for the parallel spaced relationship of the two lenses and avoid parallax. Also since both of the lenses are of the same focal length, the said arrangement is such that a better focus of the exposure lens will be secured, and subject sought to be photographed will be more sharply defined upon said film or plate.

In order that the photographic plate or film may be set in horizontal, angular or vertica1 position, without having to turn the camera out of its normal horizontal emplacement, I pivotally mount the film holder l4 upon the rear Wall 32 of the case 8. This is preferably accomplished by securing said holder to the frame Ma, aflixed to the apertured back plate Mb, and by attaching said plate to the ring 3|b, which is provided with the rim Me and annular groove 3ld rotatably engaging with the edge of the circular opening 34 in the rear wall of said case. Then by providing one edge of the plate l4b with spring stops I40 engaging with spaced openings or depressions |4d provided therefor in the adjacent wall 32, the said holder, carrying the plate or film, may be turned and held in the position desired without moving the camera.

My invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment, as above set forth is therefore to be considered in all respects as illiustrative and not restrictive, the scope of my invention being indicated by the appended claims rather than by the foregoing description, and all changes which may come within the meaning and range of equivalenc of the claims are therefore intended to loveheriibraced therein.

a I claim and des' Patent is: ire to secure by Letters 1. In a twin lens photographic camera, the combination of finder and exposure lenses secured to a mounting in fixed parallel relation; focussing rods slidably mounted upon and extending through the front wall of the camera and into the hollow thereof, the outer ends of said rods being connected with said mounting and carrying the same thereon, and each of said rods having a rack secured thereto; a manually rotatable shaft extending between and mounted upon the side walls of said camera; a cam and gear train engaging with said racks and operatively connected with said shaft; a mirror pivotally mounted within said camera; a cam follower secured to and adapted to turn said mirror upon its mounting and located to be actuated by said cam, said mirror being positioned to receive the light rays from said finder lens with the pivotal axis of said mirror at right angles to the axis of said lens; a hood opening into the top of said camera, and a fiat viewing screen mounted within said hood to move in an arcuate path therein; the center of curvature of said path being coincident with the pivotal axis of said mirror; and link and lever means mounted within said camera and connecting said mirror and screen and coordinating the relative movement thereof so that the said screen will always turn through an angle twice as great as that turned by said mirror; said link and lever means cooperating with said lenses and operating mechanism to reproduce upon said screen without parallax the same view as that cast by the exposure lens upon the sensitized film or plate of the camera.

2. In a twin lens photographic camera, the combination of finder and exposure lenses; a carrier with said lenses mounted thereon in fixed parallel relation and adapted to move said lenses simultaneously to focus the same upon the obJect to be photographed; a mirror pivotally mounted within the camera, said mirror being positioned to receive the light rays from said finder lens with the pivotal axis of said mirror at right angles to the axis of said lens; a hood opening into the top of the camera, and a flat viewing screen mounted within said hood to move in an arcuate path therein; the center of curvature of said path being coincident with the pivotal axis of said mirror, and link and lever means mounted within the camera and connecting said mirror and screen and adapted to coordinate the relative movement thereof, so that the said screen will always turn through an angle twice as great as that turned by said mirror, and so that the plane of the screen is always perpendicular to the paraxial pencil of rays coming from the finder lens and reflected upwardly upon the screen.

3. In a twin lens photographic camera, the combination of finder and exposure lenses; a carrier with said lenses mounted thereon in fixed parallel relation and adapted to move said lenses simultaneously to focus the same upon the object to be photographed; a mirror pivotally mounted within the camera, said mirror being positioned to receive the light rays from said finder lens with the pivotal axis of said mirror at right angles to the axis of said lens; a hood opening into the top of the camera, and a flat viewing screen mounted within said hood to move in an arcuate path therein; the center of curvature of said path being coincident with the pivotal axis of said mirror; and link and lever means mounted within the camera and connecting said mirror and screen and adapted to coordinate the relative movement thereof in accordance with the equation :c'=F /x, where a: is the distance from the object to be photographed to the first focal point of the lens, and x is the lens movement upon being refocussed on an object located at infinity.

JOHN H. MclLROY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,819,844 Ross Aug. 18, 1931 1,998,568 Barenyi Apr. 23, 1935 2,297,401 Gabler et a1 Sept. 29, 1942 FOREIGN PATENTS Number Country Date 651,143 Germany Oct. 8, 1937 765,541 France Mar. 22, 1940 521,452 Great Britain May 22, 1940 

